MIT physicist Deepto Chakrabarty and 2 other scientists were announced the winners of 2006 Bruno Rossi Prize for their pioneering work on understanding the exotic environment around fast-spinning neutron stars, where matter can whirl about at nearly light speed and where space itself is warped. The other winners are Tod Strohmayer of NASA Goddard Space Flight Center in Greenbelt and Rudy Wijnands of the University of Amsterdam. The prize is the top award given each year by the High Energy Astrophysics Division (HEAD) of the American Astronomical Society (AAS).

Their work, done independently and sometimes as collaborators, has been described as breakthrough in interpreting the complex signals emitted as X-ray light from millisecond pulsars. A millisecond pulsar is a type of fast-spinning neutron star in a binary system with an ordinary star. Gas pulled away from the surface of the companion star crashes onto the neutron star, spinning it up to rotation rates of hundreds of revolutions per second.

These scientists have revealed that oscillations in the emitted X-ray light can be used to measure the pulsar's spin rate and other key parameters. Their observations were made with NASA's Rossi X-ray Timing Explorer, which marks its tenth year in orbit this month.

Chakrabarty, an associate professor of physics at MIT and a researcher at MIT's Kavli Institute for Astrophysics and Space Research, is an expert on millisecond pulsars. He credits his MIT colleagues and collaborators, especially research scientist Edward Morgan, for making his discoveries possible.

"Bruno Rossi was a giant at MIT...I am humbled to receive an award named in his honor," Chakrabarty said. "The Rossi Explorer is a powerful tool to probe the environs of black holes and neutron stars."

Strohmayer, an expert on thermonuclear X-ray bursts emitted from the surface of neutron stars, credits Jean Swank, the Rossi Explorer project scientist, also at NASA Goddard, for giving him the opportunity to join the Rossi team.

Rudy Wijnands, member of the University of Amsterdam's High-Energy Astrophysics Group, discovered the first accreting millisecond pulsar. He's an expert in interpreting signals from X-ray pulsars called quasi-periodic oscillations emitted from gas whipping around the pulsar at high speeds.

The HEAD-AAS awards the Rossi Prize in recognition of significant contributions as well as recent and original work in high-energy astrophysics. The prize is in honor of Professor Rossi, an authority on cosmic-ray physics and a pioneer in the field of X-ray astronomy. The prize also includes an engraved certificate and a $1,500 award, which will be shared among the winners.